Electrical detection of magnetization dynamics in an ultrathin CoFeB film with perpendicular anisotropy.

The anomalous Hall effect (AHE) was used to investigate the magnetization dynamics of an ultrathin (1.3nm) CoFeB magnetic multilayer with perpendicular magnetic anisotropy (PMA). By directly sending a radio frequency (rf) current into a millimeter-sized film sample without any lithography process, a resonant dc voltage can be detected along the Hall direction. This method was used to study the dynamic properties of ultrathin CoFeB films, such as the gyromagnetic ratio, amplitude of PMA field, and magnetic damping. The dc voltage was proven to be the consequence of spin rectification enabled by the AHE, and the dynamic magnetization was driven by the Oersted field and spin current from the electric current in the adjacent Ta layer. [ABSTRACT FROM AUTHOR]